Whistleblowers such as Daniel Ellsberg, Thomas Drake, William Binney, and Edward Snowden; and hackers and activists such as the WikiLeaks founder Julian Assange and the former British secret service agent Annie Machon, warn us about the complete surveillance of our society.

Facebook is evil in my view, I've been saying this for years. [...] We offer up our information and it's just there on a plate for the spies to access. And we know they do through back doors and things. Yet that sort of information used to take them weeks or months to gather on an individual.

Annie Machon, former British secret service agent

They oppose intelligence agencies, governments and corporations. And for this, they are threatened, hounded and imprisoned.

Why are they so committed? What drives them? And is there a collective motive?

Digital Dissidents is a two-part documentary that goes into the heart and experiences of what it means to be a whistleblower and the nature of the quests to disclose radical truths hidden from society.

We hear the personal testimonies of whistleblowers and examine the psychology of whistleblowing.

What happens when an intelligence insider wants to reveal their country's surveillance secrets? What about if that secretive culture still affects an individual after they've become a whistleblower?

Assange, for instance, says he was never an insider: "I never had the view that one should work for these organisations."

He likens working in the NSA to being on a drug.

"A drug that made them powerful; because they were in a group they had a lot of power and that system has a way of talking about how the world works, how the United States empire is a good thing.

"And it can take a long time to wash that drug out of the system. Daniel Ellsberg has nearly entirely washed that out of his system, but the more recent whistleblowers, they still have perhaps some way to go."

Annie Machon, an ex-M15 agent, talks about being on the run after her partner became a whistleblower.

"Having lived with that sense of endemic surveillance, I can tell you it's corrosive to the human spirit. So once you lose that sense of privacy and you start to self-censor, you stop being an effective and fully integrated citizen of that country. So privacy, in my view, is a last defence against a slide towards a police state.

Intelligence services are not the only ones monitoring communications and processing massive data. Private corporations such as Google, Amazon, Facebook and Apple collect millions of pieces of information about us to analyse and monetise. How has the advent of the smartphone, which Machon calls a "spyphone", made us more visible? What do intelligence agencies and companies do with our data and how do the two collude?

Spanning the US, Germany, the UK, and Russia, we hear from the most consequential whistleblowers of the 21st century to learn their personal, and at times poignant, stories and perspectives on revealing secrets. We also hear from Stephan Mayer, a German politician on the committee investigating NSA spying, Yvonne Hofstetter, a big data expert, and Germany's former minister of culture, Julian Nida-Rumelin.

We learn what these whistleblowers, hackers and activists really think about each other. And we look at what is so wrong with our surveillance climate at large, and the price of whistleblowing on an individual's life.